Copper base alloys containing manganese, aluminum and zinc



United States Patent 3,323,913 4 CQPPER BASE ALLOYS CONTAINING MANGA- NBS-E, ALUMINUM AND ZINC Leendert BGSIEEZE], Drnnen, Netherlands, assignor to Lips {N.V., Drunen, Netherlands, a corporation of Dutch No Drawing. Filed Dec. 10, 1964, Ser. No. 417,473 Claims priority, application Netherlands, Dec. 12, 1963, 301,755 4 Claims. ((11. 75-1575) This invention relates to copper base alloys containing manganese, aluminum and zinc.

Such alloys have become known in dilferent compositions, with higher or lower manganese contents, the higher manganese alloys having no zinc and/or almost no iron or nickel.

For instance such alloys have become known which contain 2 to 4% of iron, 1 to 6% of nickel, 3.5 to 9.5% of aluminum, 15 to 35% of manganese, the balance copper and usual impurities.

Such alloys have good mechanical characteristics and a good corrosion resistance, so that they have been proposed as material f.i. for the casting of ships propellers.

This invention aims at obtaining a new alloy of the same kind but of difierent composition and having in part the same, in part better mechanical characteristics, corrosion resistance, castability, weldability and characteristics for easy extrusion in hot condition. Moreover this invention aims at obtaining an alloy of this kind which is easier to manufacture, particularly with respect to corrections to be made in the molten alloy, than such known alloys. This is obtained by giving such an alloy according to the invention a composition in which it contains: 1 to 8% of aluminum, 0 to 6% of nickel, 1 to of iron, 3 to 11% total of nickel and iron, more than 21 up to 35% of manganese and 1 to 7% of zinc, balance copper and usual impurities.

It is already known that in copper-manganese-aluminum alloys the manganese has a so-called aluminum equivalent, which means that part of the aluminum may be replaced by manganese. Such replacement has a double etfect, viz. on the one hand with respect to several mechanical characteristics and on the other hand with respect to the structure of the alloy and amounts of socalled zzand [St-phase in the alloy. For both effects manganese has the same aluminum equivalent, namely of about 0.1 to 0.2, which means that a change in the amount of manganese has a correspondingly smaller effect than a corresponding change in aluminum, but in the same direction.

The aluminum content is highly critical both with respect to the mechanical characteristics and with respect to the structure. Thus during the manufacture of the molten alloy corrections of the bath by changing the aluminum content are difficult to realize and small unintended differences in the aluminum content give considerable difierences in characteristics.

It has now been discovered that zinc is also able to replace part of the aluminum in its eifect on the mechanical characteristics and on the structure and that zinc has an aluminum equivalent of 0.3 to 0.4. Thus zinc is not so ice critical as aluminum but has more effect than manganese. Zinc also has the considerable advantage over man ganese as a substance for correction of the molten alloy that it is more economical and has a much lower melting point. Less zinc than manganese is required for the same correcting eflfect. Thus correction with zinc gives a quite preferable possibility with more freedom of manufacture.

Apart from the mechanical characteristics and the structure as to the socalled aand S-phase influencing several mechanical characteristics an important factor is the precipitation of an iron-rich phase when the alloy solidifies from the molten bath, which iron-rich phase is together with the further structural characteristics of great importance for the corrosion resistance of the alloy. For the forming of this iron-rich phase the iron and nickel contents are of great importance, but moreover it has appeared that the said precipitation is considerably influenced by the other constituents of such alloys, particularly by manganese and aluminum, and it has been found that in a certain field of aluminum and manganese contents more iron-rich phase is formed when the aluminum content is decreased and when the manganese content is increased.

The present invention is thus also based upon the idea that it is possible to obtain more freedom in influencing the precipitation of the iron-rich phase or in keeping it at a sufiicient level and thus obtaining a very good corrosion resistance while being as free as possible in varying the mechanical properties by enabling a variation within relatively wide limits of the manganese content together with the zinc and aluminum contents.

As to the said aluminum equivalent, zinc has. about twice the influence of manganese on the mechanical properties and on the structure, particularly as to (X- and fi-phase, but as zinc has little influence on the precipitation of the iron-rich phase and as manganese and aluminum in certain fields have an opposite effect on this precipitation, the wide limits of the manganese content and the presence of zinc within the limits given by the invention make it possible to obtain the desired mechanical properties and 0c and 5- structure by choosing the desired value of the total aluminum equivalent, composed of the influences of aluminum, zinc and man-ganese, while nevertheless maintaining freedom to vary the aluminum and manganese contents mutually without varying said total aluminum equivalent by varying the zinc content to obtain the desired amount of precipitation of the iron-rich phase and thus full corrosion resistance. It thus appeared possible to vary the zinc content for this purpose up to high manganese contents, namely up to 35% of manganese.

The surprising character of the present invention may appear from the fact that up to now in comparable alloys with relatively high manganese content no zinc was used at all, such as in the known alloy given above in the publication of the British Standards Institution: BS. 1400: 1961: Schedule of Copper Alloy Ingots and Copper Alloy Castings, pages to 68 for manganese-aluminumcopper alloys the total absence of zinc is taken as a basis.

If in the alloy according to the invention the total amount of iron and nickel is maintained from 3 to 11% as given above the corrosion resistance is most favourable.

3 If the manganese content is 28% or higher the aluminum content should be lower than 7% as the alloys otherwise could become too brittle.

It is preferable to manufacture an alloy according to the invention so that it contains:

Total Percent Iron and nickel 3 to 8 Manganese a a 25 to 3 Aluminum 3 to 6 Zinc 1.6 to 6 Balance copper and usual impurities.

If an alloy is required which has a relatively high elongation and ductility it is preferable according to the invention to manufacture an alloy of the following composition:

Percent Iron 2 to 4 Nickel 1 'to 3 Aluminum 3 to 4 Manganese 25 to 32 Zinc 1.6 to 4 Balance copper and impurities.

For stronger and harder alloys with smaller elonga- Balance copper and impurities.

The invention will now be explained further on the basis of several examples.

EXAMPLE I The following elements were melted together in a suitable furnace:

Percent Manganese 30.9 Iron 3 .9 Aluminum 3.8 Nickel 2.9 Zinc 2.4

Balance copper and impurities.

, This gave a rather ductile alloy with a relatively high elongation. The alloy was cast in a sand mold bonded by cement. Examination of a sample of this alloy gave the following values:

Tensile strength p.s.i 93,000 Elongation at rupture: (d.p. 5) ercent 35 Brinell hardness 152 This alloy is quite suited for extrusion.

EXAMPLE II In the same manner as given in, Example I an alloy was made which was harder with a high tensile strength and a moderate elongation, having the following composition:

Balance copper and usual impurities.

A sample of this alloy gave the following characteristics:

Tensile strength p.s.i 108,000 Elongation at rupture: (d.p. 5) -percent Brinell hardness 208 4 EXAMPLE 111 An alloy with relatively high tensile strength and good elongation was obtained by manufacturing an alloy of the following composition in a furnace:

Percent Manganese 31.2 Iron 4.0 Aluminum 3.6 Nickel 3.9 Zinc 4.0

Balance copper and impurities.

A sample of this alloy gave the following values:

Tensile strength p.s.i 98,000 Elongation at rupture: (d.p. 5) percent 26 Brinell hardness 175 EXAMPLE IV For special purposes requiring a ductile alloy the following composition of an alloy was made in the furnace:

Percent Manganese 24.9 I-ron 2. 1 Aluminum 3 .0 Nickel 2.0 Zinc 1.6

Balance copper and impurities.

A sample of this alloy gave the following values:

Tensile strength p.s.i 74,000 Elongation at rupture: (d.p. 5) percent 45 Brinell hardness 135 The invention can be realized by melting the components together in a metallurgical furnace in a manner generally known in the art.

All percentages given in the above specification and in the attached claims relate to percentages by weight of the total alloy.

What I claim is:

1. An alloy having the following weight composition: 1 to 8% aluminum, up to 6% nickel, 1 to 5% iron, more than 21 up to 35% manganese, 1 to 7% zinc, balance essentially copper, the sum of the iron and any nickel being 3 to 11%, the aluminum content being not more than 7% if the manganese content is as high as 28%, the aluminum equivalent, calculated by adding to the aluminum percentage 0.15 times the manganese percentage and 0.35 times the zinc percentage, being between 7 and 13.

2. An alloy as claimed in claim 1, the sum of the iron and any nickel being 3 to 8%, the aluminum being 3 to 6%, the manganese being 25 to 32%, and the zinc being 1.6 to 6%.

3. An alloy as claimed in claim 1, the iron being 2 to 4%, the nickel being 1 to 3%, the aluminum being 3 to 4%, the manganese being 25 to 32%, and the zinc being 3.5 to 5%.

4. An alloy as claimed in claim 1, the iron being 2 to 5%, the nickel being 2 to 6%, the aluminum being 5 to 6%, the manganese being 25 to 32%, and the zinc being 3.5 to 5.5%.

References Cited UNITED STATES PATENTS 3,134,669 5/1964 Putter et al. "-161 FOREIGN PATENTS 922,399 3/1963 Great Britain.

DAVID L. RECK, Primary Examiner. CHARLES N. LOVELL, Examiner. 

1. AN ALLOY HAVING THE FOLLOWING WEIGHT COMPOSITION: 1 TO 8% ALUMINUM, UP TO 6% NICKEL, 1 TO 5% IRON, MORE THAN 21 UP TO 35% MANGANESE, 1 TO 7% ZINC, BALANCE ESSENTIALLY COPPER, THE SUM OF IRON AND ANY NICKEL BEING 3 TO 11%, THE ALUMINUM CONTENT BEING NOT MORE THAN 7% IF THE MANGANESE CONTENT IS AS HIGH AS 28%, THE ALUMINUM EQUIVALENT, CALCULATED BY ADDING TO THE ALUMINUM PERCENTAGE 0.15 TIMES THE MAGANESE PERCENTAGE AND 0.35 TIMES THE ZINC PERCENTAGE, BEING BETWEEN 7 AND
 13. 